The Seismic method is a known technique of performing below-ground surveys. It involves the generation of a pressure or sound wave (p-wave), shear wave (s-wave), or other types of waves and transmission of same through the ground being surveyed. These waves cause relative motion of the ground, including the soil, rock or stones, and any water.
The Seismic wavefield can be received, or detected, at the surface and measured to determine information about the sub-surface. Various techniques can be used to improve the reliability of the resulting measurement, including the use of multiple surface sensors for a single seismic source. The signal and data collection can also be repeated to improve the accuracy of the measurement, such as by improving the signal-to-noise ratio.
Such techniques are known to be useful for exploration of the underground ranging in depth from about 50 to 500 meters, or more. To reach these depths, the signal sources used must be capable of transmitting significant energy into the ground. Conventional sources include explosives, large vibrating trucks, and large weight drops. A typical earth tamper, for example, generates an impact force of about 3,000 lbs. Typical vibrators generate a peak force ranging from about 11,000 lbs to about 33,000 lbs.